Machines, used particularly for the production of yarns for carpets, have been provided for a very long time, as emerges particularly from FR-A-1,455,499 and from U.S. Pat. No. 3,525,205. It has also been proposed to use such machines for treating partially drawn synthetic yarns, drawing being carried out at the double-twist spindle, as emerges from FR-A-2,414,568.
As emerges from these documents, such installations consist of a central stand which supports a plurality of identical workstations comprising, as seen in the direction of passage of the yarn:
a single-twist or double-twist spindle supporting a yarn package, PA1 means for the take-up of the yarn, PA1 a thermal treatment oven arranged either vertically (FR-1,455,499) or horizontally (U.S. Pat. No. 3,525,205), followed by a cooling zone, and PA1 means for winding up the treated yarn. PA1 a double-twist or cabling spindle supporting a package of yarn intended to be twisted or cabled together with a second yarn; PA1 means for the take-up of the yarn, making it possible to eliminate the tension which occurs as a result of the twisting or cabling operation; PA1 yarn-heating means followed by a cooling zone; and PA1 means for winding up the treated yarn. PA1 the heating means consist of a rectilinear oven arranged vertically or approximately vertically PA1 the yarn executes a to-and-fro movement inside the said oven, a return system for said yarn being provided to an extremity of said oven in order to realize this to-and-fro. PA1 the yarn is introduced into and extracted from the oven by way of its lower end; PA1 the return system is arranged at the top of the oven and is constituted by a take-up system;
In such installations, the yarn is maintained in the relaxed state during the thermal treatment and during the cooling phase prior to reeling.
Although the machines which are the subject of the abovementioned patents relate to the twisting of a single yarn, it has been proposed for a very long time to use similar machines for carrying out direct cabling operations, as emerges from U.S. Pat. No. 3,820,316. For this purpose, in such a case, the yarn coming from the package mounted on the spindle is combined with a second yarn which comes from a second reel mounted in a stationary manner on the stand of the machine and which is fed through the shank of the said spindle as far as a cabling head arranged in the extension of the latter.